高精度分光を目指した CaH + の生成とトラップ. 富山大学・理 森脇喜紀. Motivation. Spectroscopy of 40 CaH + the pure vibrational transition ( v= 0 , J= 0 , F= 1/2 , M= ±1/2) → ( v= 1 , J= 0 , F= 1/2 , M= ±1/2) can potentially be measured with an uncertainty of 10 -16 by use of
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Spectroscopy of 40CaH+
thepure vibrational transition (v=0, J=0, F=1/2, M=±1/2) → (v=1, J=0, F=1/2, M=±1/2) can potentially be measured with an uncertainty of 10-16
by use of
simultaneous trapping with Ca+ ions
quantum logic measurement
Application to the test of the time invariance of fundamental constants e.g. electron-proton mass ratio
P.O.Schmidt et al.
Science 309, 749(2005)
Shelkovnikov et al. PRL100, 150801 (2008)
Vibrational transition of SF6Dn/n～10-14
Kajita and Moriwaki J. Phys. B 42, 154022(2009)
CaH+ （v = 0, J = 0, F = 1/2, M = ±1/2）
→ （v = 1, J = 0, F = 1/2, M = ±1/2） transition
f = 42.24 THz (7.1 mm)
(1) Natural linewidth 2.5 Hz
(2) Zeeman shift (magnetic field < 1 G) < 1.3 x 10-17
(3) Stark shift induced by the trapping electric field < 10-17
(4) Electric quadrupole shift iszerobecause ofF = 1/2
(5) Stark shift induced by probe laser light is most dominant
~ 1.2 x 10-16 with saturation power (32 mW/cm2)
(1) Laser ablation of Ca containing solids
(2) Ca++H2 → CaH+ +H
Georgiadis et al. J. Chem. Phys. 92, 7060 (1988)
Ca+ (4p 2P 1/2) + H2 CaH+ + H
Vdc+Vac cos Ωt
LIF signal is proportional to the number of Ca+ ions.
With H2 buffer gas, LIF decay significantly.
Ca+ (4p2P1/2)+H2→CaH++H ?
Buffer gas : H2 (99.99995%)
The mass signal (m=41u) is normalized by that of m=40 u
M=41u signals appear with the laser irradiation.
With D2 buffer gas, m=42 u signals are observed.
Production of CaH+, CaD+ has been confirmed !
Without 397nm and 866nm laser, LIF decays slowly.Without 866 nm laser, LIF decays fast although the 2D3/2 state is optically pumped.
Ca+ (3d 2D 3/2) + H2 CaH+ + H
Photoassociated ion loss?
There have been no experimental data on CaH+.
Needs for reliable theoretical data
ab initio calculations of Ca+-H potential curves
electric energy levels, vibrational levels, Rotational constants, transition dipole moments
by M. Abe (collaborator)
Ca+2P [(4p)1] + H 2S [(1s)1]
Ca+2D [(3d)1] + H 2S [(1s)1]
Ca+2S [(4s)1] + H 2S [(1s)1]
a 4th order MBPT: Canuto et al. Phys. Rev. A. 1993.
b Two-elec. valence CI and core polarization: Boutalib et al. Chem. Phys. 1992.
Cryogenic ion trap:
99% of CaH+ ions are localized in the (v,J)=(0,0) state at T=4 K
H2 vapor pressure ~ 10-7 Torr
小山達也, 中口利彦, 日比野誠(学生)